Conventionally, an armature of a DC motor includes a coil and a commutator, which is electrically connected to the coil. In a DC motor described in Patent Document 1, a coil is wound around an armature core. A free end, or an end of a conductor, extends from the coil. The free end is connected to a connecting portion provided in a segment of the commutator.
However, in the DC motor, a step of connecting the free end, or the end of the conductor extending from the coil to the connecting portion of the commutator, is an separate and independent step from a step of winding the coil around the armature core. In other words, connection of the conductor to the connecting portion of the commutator is complicated.
The end of the conductor is connected to the connecting portion of the commutator through, for example, welding at a position on the coil, or a position at which the coil is provided as viewed in the axial direction. Therefore, such connection is hampered by the coil, causing damage to the coil, or a short circuit.
These problems happen not only in motors having brushes and a commutator. Patent Document 2 discloses a brushless motor in which a circuit device, not a commutator, is connected to a portion of a conductor. Specifically, a portion of the conductor, which forms a coil and a connecting wire, is electrically connected to a terminal assembled with a stator core. The terminal is electrically connected to a connecting portion provided in the circuit device, which supplies a drive current to the coil.
However, since the brushless motor includes the terminal, the number of the components of the motor increases. Further, manufacture of the brushless motor involves a step of assembling the terminal with the stator core and a step of electrically connecting the conductor to the terminal, which is, for example, a step of pressing the conductor against the terminal and fusing the conductor to the terminal. These steps complicate the manufacture of the motor.
As another typical example, there is a case in which a coil is wound around a plurality of teeth extending radially from an armature core by way of concentrated winding. Patent Document 3 discloses a radial connecting member that connects an armature core having radial teeth to a rotary shaft. A coil is wound around the armature core by way of concentrated winding, making it easy for the armature core to generate heat. However, since the connecting portion has a hollow portion, or a clearance, the armature core exhibits improved heat radiating performance.
Nonetheless, by providing the connecting member in the armature core, the number of the components of the armature core increases. Further, since the coil is wound around the armature core by way of concentrated winding, the lamination factor of the coil becomes great, decreasing the size of the clearance. The armature core thus easily generates heat, making it desirable to improve the head radiating performance of the armature core.    Patent Document 1: Japanese Laid-Open Patent Publication No. 2003-299292    Patent Document 2: Japanese Laid-Open Patent Publication No. 11-356024    Patent Document 3: Japanese Laid-Open Patent Publication No. 2004-88902